Deposition of films in a process chamber such as, for example, a physical vapor deposition (PVD) chamber has become increasingly different as the size of features in a substrate continues to shrink. In such cases, metallic materials such as, for example, tantalum (Ta) and tantalum nitride (TaN) are frequently chosen as materials to deposit on a substrate to create a barrier film. However, because TaN is a nitride film, TaN has lower cohesion and is more brittle than a metallic film material. As such, during deposition of such materials, the thickness of a film deposited on an upper portion of a process shield of a conventional process kit is greatest, resulting in the flaking off or detachment of the material due to brittleness and poor adhesion/cohesion to the process kit. The flaking is further exacerbated by the thermal expansion and contraction of the process shield caused by bombardment of neutral or ionized material during process step and return to room temperature during an idle state.
Accordingly, the inventors have provided embodiments of an improved collimator.